1. Field of the Invention
This invention pertains generally to electrical connectors having a plurality of contacts carried by flexible resilient dielectric material and particularly to electrical connectors in which a large number of separate electrically conductive linear elements are fixed in an array between two spaced planes, each linear element having a first end in one plane and a second end in the second plane, the ends in one plane being in the same relative position and having the same relative spacing with respect to each other as their opposite ends in the other plane. The linear elements are held in the array by means of a resilient, electrically non-conductive elastomer such that a large number of small diametered electrically conductive linear elements are spaced in accurate alignment with each other through a sheet or plate of the dielectric elastomer. The connectors provided by this invention are adapted for picking up electrical charges and small currents from selected points in one plane and conducting them to corresponding points in another plane.
2. Description of the Prior Art
Numerous electrical connector devices have been proposed in the prior art utilizing a large number of wires extending generally through a body of elastomeric insulating material, the wires extending between spaced surfaces parts of the elastomer generally through non-rectilinear paths. Such connectors generally required a wire of metal having good spring characteristics as well as satisfactory electrical performance and resistance to chemical degradation to ensure satisfactoy electrical conductivity between the two surfaces of the connector. The wires were typically made of phosphor bronze, brass, Monel, copper, stainless steel, and other metals having inherent spring-like properties and of sufficient hardness to pierce any oxide coating which might be present on the electrical conductors sought to be connected by the connector. The prior art failed to appreciate that the necessary forces for elastic recovery of the wires might be found in the elastomeric body rather than the wire.
The cross-sectional dimension of the linear conductive elements and the spacing between adjacent elements are two variables which have been previously considered as subject only to the designer's choice, depending on the number of exposed wires per unit surface area of the connector sought by the designer. Close packing of the elements has been considered optimum by much of the prior art. Surprisingly, it has been found that if the plurality of the electrically conductive linear elements constitutes much in excess of 10% of the volume of the connector, the connector behaves less as cushioning elastomer and more like an inflexible, incompressible solid.
The prior art has generally assumed that a disadvantage was to be experienced when a connector contained electrically conductive linear elements rectilinearly extending normally from one face of the connector to a second parallel face of the same connector. In general, the electrically conductive elements of the prior art embedded in a matrix of elastomeric material were corrugated, angularly bent, arcuately curved, or in some other manner extended through the elastomeric matrix in non-rectilinear paths. Known instances of linear elements rectilinearly extending through a matrix of dielectric material required that the matrix be a non-elastomeric, hardened solid block of material such as glass.
None of the prior art considered the difference of behavior of electrically conductive linear elements which can be considered slender columns rather than compression blocks. When subjected to a compressional load along the axis, a slender column tends to experience an elastic buckling behavior rather than a simple compression. The behavior is, as the name implies, elastic in nature and is not permanently deforming. By designing the electrically conductive linear elements in a connector to fit the slender column criteria, it is no longer necessary to artificially introduce curves, bends, corrugations, or the like, to ensure elastic deflection under a compressional load.
The prior art has also failed to consider the advantages to be experienced with electrically conductive linear elements which are not wholly metallic. Particularly advantageous features are to be found in the use of electrically conductive linear elements of foil wrapped textile strands, metal-plated resin monofilaments, carbon-loaded nylon and other carbon yarns. Examples of the prior art may be found in U.S. Pat. Nos. 2,885,459; 3,126,440; 3,542,939; 3,714,706; 3,795,037; 3,862,790; and 3,852,878. Other prior art which may be of interest can be found discussed in these patents.